One man’s trash is another man’s treasure – especially if he’s trying to save on his electric bills. At least, that’s what Terry Johnson and Mel McMinn seemingly learned when they said they reportedly transformed old cans into an energy-saving solution for their abode.
Wood once provided the United States with nearly all of its energy – until fossil fuels such as coal and petroleum replaced it in the late 19th century. And now the U.S. and countries beyond are seeking out renewable sources of energy to power homes, vehicles and more.
One such source of renewable energy is the sun. Solar thermal energy, for instance, relies on the sun’s rays to heat a fluid that sizzles into steam. Inside of a turbine, steam then becomes mechanical energy that powers a generator that puts out usable energy.
Then, of course, there are solar panels, which harness the sun’s power in order to split electrons away from atoms. This simple separation creates a current of electricity between photovoltaic cells, which can now be manufactured even thinner than a strand of human hair.
Adding these panels to a domestic or commercial property can have huge benefits. Aside from lowering the cost of utility bills, solar energy is much better for the earth than burning fossil fuels. But the upfront costs – an average of $18,840 per panel in 2018 according to website energysage – are likely to prevent many from making the switch.
Nonetheless, some pioneering homeowners have figured out how to harness the power of the sun’s energy without a huge financial investment. Terry Johnson and his partner, Mel McMinn, for instance, were frustrated that winter temperatures were frequently higher outside of their New Zealand home than inside of it.
“It was one of those houses which was pleasantly cool in the summer, but freezing in the winter. We needed something to make it thermally efficient but didn’t have a big budget,” Johnson told Stuff. So he and McMinn sought out a solution – and found an ingenious plan for building an at-home solar heat collector.
McMinn wrote on her blog, Frugal Kiwi, that their project began with “a whole heap of cans.” She and Johnson collected more than 300 old cans over a single summer, in fact. They also added to their own collection with donations from friends and discarded cans that they found.
After that, Johnson grabbed a pair of tin snips, which are shears stronger and more precise than regular scissors. He then cut slits into the tops of all the cans to turn them into baffles, which would help guide air in and out of the panel when finished.
With all of the cans opened up, Johnson glued them into columns. Then he sprayed each finished cylinder with a matte black paint. The D.I.Y.-er had read that “you got improved performance with an all-around spray” rather than painting the cans only on their sun-facing side, McMinn wrote on her blog.
Of course, the can columns would require an enclosure, so Johnson used an entire sheet of plywood as the base of his solar structure. “Many people build with old window panes, so don’t think they all have to be so massive. It’s just that we weren’t messing about when we built ours,” McMinn wrote.
But the panel frame would need a few more touches to make it possible for it to work as a solar heater. For instance: a lower manifold would let air into the panel, while an upper hole would allow air to escape once heated. In the middle of the panel, can-sized notches would also hold the painted columns in place.
To complete the construction, Johnson put the painted columns into place. He ended up with 17 16-can towers. Over that, he affixed a sheet of polycarbonate to cover the cans while still allowing them plenty of exposure to the sun.
As mentioned above, the solar panel would have two holes through which cool air would enter and warm air would exit once heated. For Johnson and McMinn, the current would circulate out of and into their living room, so they had to drill two holes into their drywall. In each opening, they installed fans to push out heat and suck in chilly air.
The finished product doesn’t work like a traditional heater; it doesn’t pump hot air into a room to instantly raise its temperature. As McMinn described, “The heat… doesn’t immediately feel like a huge boost when it comes on.”
However, she wrote, “The thermal mass of the whole large space is lifted by several degrees.” For instance, before the installation of their homemade panel, the home’s morning temperature typically ranged from 46 to 55 degrees in winter. With the panel, they saw that span rise to between 59 and 63 degrees.
And, with that natural boost, McMinn and Johnson were then able to supplement their solar panel with a heat pump to increase the temperature another five degrees. “It is much cheaper to heat the house […] from 63 degrees than it is to do from 55 degrees,” McMinn explained.
The can-do duo built the entire panel for about $330, which McMinn described as “out of the ‘fun project’ budget range and into ‘investment’ range.” However, she and Johnson later told Stuff that they only had to spend an estimated $1.50 per year to keep the panel running.
Six years after installing their panel, McMinn and Johnson said in July 2018 that they had since moved into another home, so they weren’t sure if their creation was still up and running. Their new property was insulated and double-glazed, so they didn’t need any additional solar heating, either.
Nevertheless, the pair said the solar-panel project could suit the average home as well as sheds or warehouses. Johnson and McMinn also noted how many technological advancements made it easier and cheaper to heat homes. “There is some very interesting technology out there now,” Johnson remarked.